Monitoring, modeling and harvest management of non-native invasive green iguanas on Grand Cayman, Cayman Islands

Rivera-Milán, Frank F.; Haakonsson, Jane

doi:10.1007/s10530-020-02233-5

Cited by 12 publications

(17 citation statements)

References 35 publications

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“…Detection probability increased from 2017 to 2019 but was overall low (<0.5) across all years. Nevertheless, detection probability estimates were similar to/higher than those from comparable studies (Bock et al, 2016; Rivera‐Milán and Haakonsson, 2020). However, when an iguana was previously observed, detection probability was equal across years.…”

Section: Discussionsupporting

confidence: 82%

Hurricane‐associated population decrease in a critically endangered long‐lived reptile

et al. 2022

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Catastrophic events, like hurricanes, bring lethal conditions that can have population‐altering effects. The threatened Caribbean dry forest occurs in a region known for its high‐intensity hurricane seasons and high species endemism, highlighting the need to better understand hurricane impacts in combination with habitat fragmentation and loss. However, such studies remain rare and for reptiles are mostly restricted to Anolis. Here, we used single‐season occupancy modeling to infer the impact of the intense 2017 Atlantic hurricane season on the critically endangered Lesser Antillean Iguana, Iguana delicatissima. We surveyed 30 transects across eight habitats on St. Eustatius during 2017–2019, which resulted in 344 individual surveys and 98 iguana observations. Analyses of abundance and site occupancy indicated both measures for 2018 and 2019 were strongly reduced compared to the pre‐hurricane 2017 state. Iguanas at higher elevations were affected more profoundly, likely due to higher wind speeds, tree damage, and extensive defoliation. Overall, our results indicate a decrease in population estimates (23.3%–26.5%) and abundance (22%–23.8%) for 2018 and 2019, and a 75% reduction in opportunistic sightings of tagged iguanas between 2017 and 2018. As only small and isolated I. delicatissima populations remain, our study further demonstrates their vulnerability to stochastic events. Considering the frequency and intensity of hurricanes are projected to increase, our results stress the urgent need for population‐increasing conservation actions in order to secure the long‐term survival of I. delicatissima throughout its range. Given the projected increase and poleward shift of hurricanes, our study provides important insights from a non‐model species.

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Section: Discussionsupporting

confidence: 82%

Hurricane‐associated population decrease in a critically endangered long‐lived reptile

et al. 2022

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“…Investigation into the 2014 green iguana mortality event was limited to field observation and postmortem examination, and antemortem diagnostics were not performed. In 2019, in conjunction with the Cayman Islands Department of Environment’s green iguana culling program [ 5 ], choanal and cloacal swabs were collected from 15 culled, apparently healthy, free-ranging green iguanas at the QEIIBP. No additional diagnostics were performed in these animals.…”

Section: Methodsmentioning

confidence: 99%

“…Green iguanas were introduced to western Grand Cayman and became evident in the wild in the late 1980s and early 1990s. This species proved to be highly invasive, and by 2017 had reached an estimated population size on Grand Cayman of 1.3 million individuals, distributed island-wide but with highest density in human-modified habitats throughout the island’s western districts [ 5 ]. Due to this overabundance, culling efforts have been underway since October 2018 as a measure to keep the green iguana population under control [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Systemic Helicobacter infection and associated mortalities in endangered Grand Cayman blue iguanas (Cyclura lewisi) and introduced green iguanas (Iguana iguana)

et al. 2021

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The Blue Iguana Recovery Programme maintains a captive breeding and head-starting program for endangered Grand Cayman blue iguanas (Cyclura lewisi) on Grand Cayman, Cayman Islands. In May 2015, program staff encountered two lethargic wild Grand Cayman blue iguanas within the Queen Elizabeth II Botanic Park (QEIIBP). Spiral-shaped bacteria were identified on peripheral blood smears from both animals, which molecular diagnostics identified as a novel Helicobacter species (provisionary name Helicobacter sp. GCBI1). Between March 2015 and February 2017, 11 Grand Cayman blue iguanas were identified with the infection. Two of these were found dead and nine were treated; five of the nine treated animals survived the initial infection. Phylogenetic analysis of the 16S rRNA gene suggests Helicobacter sp. GCBI1 is most closely related to Helicobacter spp. in chelonians. We developed a Taqman qPCR assay specific for Helicobacter sp. GCBI1 to screen tissue and/or blood samples from clinical cases, fecal and cloacal samples from clinically healthy Grand Cayman blue iguanas, including previously infected and recovered iguanas, and iguanas housed adjacent to clinical cases. Fecal and/or cloacal swab samples were all negative, suggesting that Grand Cayman blue iguanas do not asymptomatically carry this organism nor shed this pathogen per cloaca post infection. Retrospective analysis of a 2014 mortality event affecting green iguanas (Iguana iguana) from a separate Grand Cayman location identified Helicobacter sp. GCBI1 in two of three cases. The source of infection and mode of transmission are yet to be confirmed. Analysis of rainfall data reveal that all infections occurred during a multi-year dry period, and most occurred shortly after the first rains at the end of seasonal drought. Additionally, further screening has identified Helicobacter sp. GCBI1 from choanal swabs of clinically normal green iguanas in the QEIIBP, suggesting they could be asymptomatic carriers and a potential source of the pathogen.

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“…On Grand Cayman, regular government-supported monitoring efforts revealed that the IAGI population was doubling each year. These data informed annual removal targets that managers used to halt rapid population expansion (Rivera-Mil an & Haakonsson, 2020), while spatial distribution analyses allowed directed response to areas that maximized culling efforts.…”

mentioning

confidence: 99%

“…In response, countries have attempted government‐sanctioned culling campaigns, costing millions of USD, to reduce the abundance of invasive iguanas (Rivera‐Milán & Haakonsson, 2020). For example, since 2018 on the island of Grand Cayman, the government has culled >1.2 million invasive alien Green Iguanas (IAGI) at the cost of 7.2 million USD.…”

mentioning

confidence: 99%

The global need to address threats from invasive alien iguanas

Knapp

Grant

Pasachnik

et al. 2020

Animal Conservation

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Monitoring, modeling and harvest management of non-native invasive green iguanas on Grand Cayman, Cayman Islands

Cited by 12 publications

References 35 publications

Hurricane‐associated population decrease in a critically endangered long‐lived reptile

Hurricane‐associated population decrease in a critically endangered long‐lived reptile

Systemic Helicobacter infection and associated mortalities in endangered Grand Cayman blue iguanas (Cyclura lewisi) and introduced green iguanas (Iguana iguana)

The global need to address threats from invasive alien iguanas

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